In the Neotropics the Orthotrichaceae contain four genera and about 60 species. The traditional recognition of the Orthotrichaceae contained two major elements which are not most closely related in terms of their evolutionary history, in other words the two elements have been maintained by shared primitive characters (cf. De Luna, 1995). At least two families are best recognized, the Orthotrichaceae s. s., in the Neotropics including for example Orthotrichum and Zygodon, and the Macromitriaceae including Groutiella, Macrocoma, Macromitrium and Schlotheimia. Amphidium previously placed in the Orthotrichaceae is now treated as a member of the Dicranaceae.

Study guide. Some of the species can be identified by the morphological features of the leaves, however sporophytic features (e.g., stomata type, immersed or superficial, and peristome type and ornamentation) are essential in Orthotrichum and Zygodon. A cross-section, just above midleaf, is useful for examining the ornamentation of laminal cells.

Plants small to large and robust, forming tufts. Stems erect, few to several branched; central strand usually absent; pseudoparaphyllia and paraphyllia absent; radiculose, occasionally tomentose. Leaves often crispate or flexuose when dry, linear- to oblong-lanceolate or oblong-lingulate, smooth to occasionally rugose or undulate, plicate or smooth, apex acute to acuminate, rarely obtuse, base occasionally decurrent; margins plane to reflexed or recurved, entire to serrulate or serrate, elimbate; costa single, usually strong, ending well below apex to long excurrent; laminal cells thick-walled, upper and median cells isodiametric to elongate, smooth, mammillose or papillose; basal cells usually elongate; alar cells rarely differentiated. Autoicous or dioicous. Perichaetia terminal on stems, leaves often differentiated. Setae short elongate, smooth, often twisted. Capsules immersed, emergent or exserted, mostly erect, urn ovoid or ovoid-cylindrical, ± symmetric, smooth or more often ribbed or furrowed, neck usually distinct, exothecial cells usually thick-walled, stomata superficial or immersed; annulus often persistent; operculum short to long rostrate, less often mammillate; peristome double, single or variously reduced to absent, exostome teeth 16 or in 8 pairs, smooth to more often papillose; endostome often reduced, smooth or papillose. Calyptrae cucullate or mitrate to campanulate with base usually lobed, plicate or smooth, naked or hairy. Spores spherical, usually papillose.